In the tobacco industry, cellophaning machines are used, which are capable of forming the packets into stacks, each defined by a first and a second packet, with the second packet superimposed on the first, and with a major lateral surface of the second packet contacting a corresponding major lateral surface of the first packet. The stacks of packets are normally fed successively in a given direction along a track extending in a plane parallel to said major lateral surfaces, and through an unloading station where the stacks are unloaded onto an unloading conveyor and fed to an input of a cartoning machine.
The packets coming off cellophaning machines are normally subjected to a finish operation, in which the packets are heated to heat-shrink the overwrappings. For this to be done properly, without wrinkling the overwrappings, both the major lateral surfaces of each cellophane-wrapped packet must be heated, which is relatively easy to do on cellophaning machines on which the packets are conveyed one by one. The same does not apply, however, on cellophaning machines of the type described above, on which the packets are conveyed stacked in pairs, on account of the mutually contacting major lateral surfaces of the packets in each stack not being accessible directly.
U.S. Pat. No. 6,511,405B1 discloses an apparatus for producing cigarette packs of the hinge-lid-box type; in order to improve the outer appearance of the cigarette packs, once an outer wrapper has been provided and sealed the cigarette packs are conveyed through a shrinking station and subjected to the action of heat in the region of the large-surface-area pack sides, in particular in the region of upwardly directed front sides. For this purpose, heating plates are positioned in the region of the shrinking station and transmit heat to the upwardly directed surfaces of the cigarette packs.
U.S. Pat. No. 5,462,401A1 discloses a method of separating two superimposed rows of cigarette packets originally in direct contact with each other, whereby the two superimposed rows are fed into the input station of a separating device in a first direction parallel to the longitudinal axis of the rows; and are fed in a second direction, perpendicular to the first direction, to a separating station where they are separated by raising the top row and subsequently inserting, between the separated rows, a separating plate which is maintained between the rows as these are removed from the separating station in a third direction parallel to the first.